First of all, epic post. I normally wouldn't have committed to reading the whole thing but because you spoke of two of my 3 favourite franchises (Star Wars being the top) I committed and it was great.

Pull up a chair, we going to be here for a while.

Joker to Batman is like peas in a pod. Joker is Batmans complete opposite, they both exist for each other. Joker embodies anti establishment more like Anarchy. He is not a Vilen in a sense he is bad. He just want the world to end in it's current form. Batman is the person he sees keeping it that way.

This is why Joker and Batman films peak. They are two polar opposites. Which is why Ben Afflic sucks as Batman, Joker has taken a seat. Not to mention Heath Ledgers portrail of Batman could never be beat. The new Joker Origins film comes close. But it was oh so fucking good. I loved it. Best DC film on the planet. The fact they are using the Joker from suicide squad means I'll watch it. Had they gone near Heath Ledgers, the film would have flopped.

Now, onto the question

There is a character in Marvel that is similar to Batman, except one thing. This character is the embodiment of both Batman and Joker and brings a whole new level of personality to the universe. Tony Stark "I am Iron Man".

Stark is Joker but with cash. Like Batman he wants to protect the world so does Joker, but the Joker wants to protect his world which is much like the world Tony Stark wants. See, Tony doesn't want a peaceful world as exhibited in the films he can not exist in a peaceful world. He needs chaos and destruction because his character is one of destruction and chose.

This is why Iron Man films flopped. He had no equal (they didn't flop but I didn't like them) they tried to bring in Thanos to be his nemesis but Thanos never was. It was Thor. Thor is a God, he was good. Thanos was Stark but with the power not the money. Tony's power was money. They were the same character.

If the Joker entered Marvel, he would be friends with Stark and they would dominate.

There is Daredevil but again, not a comparison. Or perhaps even Loki. Loki wasn't an evil character he was good, just enjoyed a prank and was always trying to get payback on Thor. He may have tried to annihilate humans, but we are not his race. We are just another planet. He wanted to look after his people and serve them. The Joker would find his match with Loki in Asguard.